The most widely used methods to treat cancer are surgery, radiation and chemotherapy. Cancer patients often receive a combination of these treatments and about half of all patients receive chemotherapy. Unfortunately, chemotherapeutic agents have significant limitations relating to their toxic effect on the patient and the efficacy of a particular dosage to target and kill tumor cells.
Most chemotherapeutic agents kill cancer cells once they begin to undergo division and replication. Cells are killed by disrupting cell division. For example, a chemotherapeutic agent may prevent the formation of new DNA or block some other essential function within a cell. Some chemotherapeutic agents may work by inducing apoptosis, essentially causing the cells to commit suicide by triggering the cells' programmed death process. Although these agents are effective for treating cancer cells that generally grow rapidly through unregulated cell division, they also kill healthy non-cancerous cells as they undergo ordinary cell division. This toxic effect is particularly apparent in fast-growing normal cells, such as bone marrow cells, those in the digestive tract, hair follicles, and reproductive cells. Because chemotherapy harms healthy tissue, the effectiveness of a drug is limited by its dosage levels and treatment frequency such that it should not exceed the tolerance levels for non-cancerous cells. Moreover, the chemotherapy regimen often dramatically diminishes the quality of a patient's life through its physical and emotional side effects. Without the ability to target the drug exclusively to cancerous tissue, chemotherapy dosages must be kept within a range (i.e., the therapeutic index) that healthy tissue can tolerate, thus often reducing the optimal effectiveness of chemotherapy on diseased tissue.
If the toxicity of chemotherapeutic agents could be reduced, then practitioners would be able to increase the dosage of a drug without the resultant unacceptable side effects. Increasing efficacy in a drug can be translated into a decreased dosage of drug, which again minimizes the potential harmful effects on a patient while offering maximum benefit. Decreasing dosage by increasing efficacy of a chemotherapeutic drug together with a reduction in toxic side effects would lead to improvement of the patient's quality of life through controlling the tumor and through reducing harmful side effects.
To date there have been various approaches to balancing effectiveness of chemotherapy treatment with the harmful side effects. For example, some approaches involve spreading out the chemotherapy treatments by giving smaller doses more frequently in order to help a patient better tolerate the treatment. Other approaches include adding additional substances to the chemotherapy regime. Such substances include those that putatively combat the noxious side effects (such as nausea) of the chemotherapeutic agents and allow the chemotherapy drug to be better tolerated by the patient. Such substances can also allow higher doses of drug to be used to combat the cancer because the patient's tolerance of the chemotherapeutic agent can be improved or increased.
Despite the advances that have been made in chemotherapeutic regimens, there remains a significant unmet medical need for increasing the efficacy of chemotherapeutic agents while at the same time reducing their toxicity. There is a need for therapies to more effectively combat cancer yet at the same time provide patients with a better quality of life during treatment by reducing the harmful and debilitating side effects of most chemotherapeutic treatments.